KEEPING SCORE: In Europe, Germany's DAX was down 0.9 percent at 12,906 while France's CAC 40 fell 0.8 percent to 5,330. The FTSE 100 index of leading British shares was 0.2 percent lower at 7,311. U.S. stocks were poised for losses at the open too with Dow futures and the broader S&P 500 futures down 0.3 percent.

US TAX CUTS: There's some uncertainty in markets as to the progress of a big overhaul of the U.S. tax system and whether there will be a vote later Friday. On Thursday, Senate Republicans rewrote the bill behind closed doors and weighed scaling back the tax cuts in the legislation to secure crucial support.

ANALYST TAKE: "The ability to resume a bullish theme will come down to whether the Senate is able to overcome objections from three Republican senators, with a host of talks scheduled for this afternoon," said Joshua Mahony, market analyst at IG.

OIL SPIKE: Oil prices rose further, a day after the OPEC cartel and a group of allied oil-producing nations agreed to extend crude output cuts until the end of next year, continuing a policy that led to a significant rise in the price of oil over the past year. At the same time, the 24-nation alliance led by OPEC member Saudi Arabia and Russia gave notice that it stands ready to revisit the move if price increases bring U.S. shale operators — who suspended operations while crude was cheap — rushing back into the market. The benchmark New York rate was up 47 cents at $57.87 a barrel while Brent, the international standard, rose 63 cents to $63.30 a barrel.